1. Field of the Invention
This invention relates to a security system for monitoring specified alarm or trouble conditions at various sensor locations, correlating the sensor information in accordance with stored instructions, and transmitting appropriate signalling information by radio or telephone to subscribers selected pursuant to such instructions. The signalling information may be in the form of a speech-synthesized message.
2. Description of the Related Art
U.S. Pat. No. 4,462,022, issued Jul. 24, 1984, to Stolarczyk, discloses an alarm system wherein a plurality of sensors at different locations transmit radio signals to a master control station, the signal from each sensor being modulated by an identifying pulse code. The master control station comprises a microprocessor which translates the code signal into an alarm signal signifying that the particular sensor is operative, and the alarm signal sounds an alarm at the master station or may be transmitted to a remote central station. However, supervisory personnel must be present at the control station or the remote central station in order to determine the source and condition of the alarm, who should be notified to take appropriate action and to give such notification to such person.
U.S. Pat. No. 4,442,426, issued Apr. 10, 1984 to Heuschmann et al., discloses an alarm system in which mobile transmitters produce coded signals identifying each transmitter. Upon reception at a receiving center the signal actuates an alarm. This system, like the previous one, necessitates the presence of supervisory personnel at the receiving center to determine the source and condition of the alarm, who to notify to take appropriate action, and to give such notification.
U.S. Pat. No. 4,257,038, issued Mar. 17, 1981 to Rounds et al., discloses a coded security system in which a plurality of sensors at monitored locations transmits pulse-coded radio frequency signals identifying particular conditions occurring at those locations. Upon detection of such coded signals at a central alarm station an alarm indication is produced which signifies to personnel thereat that such signal must be decoded to identify the particular condition at a particular location, whereby they can initiate corrective measures.
U.S. Pat. No. 4,455,511, issued June 19, 1984 to Lemelson, discloses a remote control system in which a central monitoring station which includes a microprocessor and various sensors connected thereto analyzes the signal from any sensor and produces a digitally encoded signal identifying the condition monitored thereby. This signal, in the form of coded tones, is transmitted by radio to one or more portable or statellite receivers which produce therefrom a corresponding audible alarm. Alternatively, either the microprocessor or the satellite receiver may convert the received signal to speech-synthesized form so that a person in the vicinity is verbally advised of the monitored trouble condition and location. Such a system is not adapted for monitoring a large number of remote monitored locations and conditions, and selecting which particular subscriber to notify or page concerning occurrence of a particular alarm condition at a particular location. When there are hundreds or thousands of monitored sites and paging stations, it becomes essential that signals identifying a particular trouble condition at a particular site only be provided to the specific subscriber concerned with that condition and site. It is also essential that the information transmitted to the subscriber be correlated with information relevant to the particular trouble condition. For example, not merely that the temperature of a patient at a monitored site has risen, but whether it has reached a predetermined level. It may also be desirable to indicate whether the temperature has been trending upward or downward over the past several hours. Such correlation of the condition detected by a sensor with other information, and determination of the appropriate subscriber to be notified together with notification of such subscriber without intervention by supervisory personnel, has not heretofore been available.